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SUMMARY:Making Boolean operations robust - Julian Smith\, Rainbow Group\, 
 University of Cambridge Computer Lab
DTSTART:20051117T141500Z
DTEND:20051117T151500Z
UID:TALK4527@talks.cam.ac.uk
CONTACT:Alan Blackwell
DESCRIPTION:There are serious problems in computing the union\, intersecti
 on or difference between two boundary mesh shapes when using approximate a
 rithmetic\, because inaccuracies and inconsistencies in the low-level calc
 ulations can lead to an invalid result.  Two types of error can occur: top
 ological errors\, usually manifested as cracks in the 'boundary'\, and geo
 metrical errors\, often manifested as a self-intersecting 'boundary'.  The
  traditional approach taken by system developers is to invest effort in tu
 ning a system so that it tends to avoid catastrophic failure for typical a
 pplications.  Others have adopted the approach of resorting to exact arith
 metic to achieve 100% reliability.  I shall describe the algorithm I devis
 ed\, based on standard machine arithmetic\, that provably generates a topo
 logically valid result.  I shall also describe my latest work that address
 es the issue of geometric errors.
LOCATION:Rainbow Room (FS07)\, Computer Laboratory
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